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Home >> Chrysler >> 2011 >> 300 Base, Gas >> Repair and Diagnosis >> External Pages >> Different car >> Section 98 (6.7L Diesel - DTCS - P040D To P1191 - 3500 Cab & Chassis) >> Diagnosis and Testing >> P0420-Catalyst Efficiency Below Threshold >> Code Description >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
AFTERTREATMENT DIESEL OXIDATION CATALYST HAS BEEN REMOVED FROM THE VEHICLE
EXHAUST GAS TEMPERATURE SENSOR 1 AND EXHAUST GAS TEMPERATURE SENSOR 2 HARNESS CONNECTORS REVERSED
AFTERTREATMENT DIESEL OXIDATION CATALYST IS DAMAGED OR NOT FUNCTIONING PROPERLY
AFTERTREATMENT DIESEL OXIDATION CATALYST INLET AND/OR OUTLET TEMPERATURE SENSORS ARE DAMAGED/FAILED
IMPROPER FUELING
WIRE HARNESS

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to  PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE - 6.7L  .